Many experts believe that 40% or more of energy loss in a home is due to air leakage. Some of that energy loss is due to wind, and some is due to the atmospheric pressure differences between the inside and the outside of the building. A significant portion of the air leakage is due to the “chimney effect” or the escape of rising heated air from the house into the attic. Air escapes through gaps that are virtually invisible, so few people even know that the gaps are present, let alone, how to seal the gaps. Specifically, there are gaps between the top plates of framed walls and the drywall that is installed against them. These gaps occur because of the imperfect fit and irregular size of the framing members. The gaps occur in all interior and exterior walls and on both sides of the interior walls. Since the gaps are often 1/16″-⅛″ or more in thickness, and may occur in literally hundreds of running feet of walls at the intersection with the attic, the net effect is a huge breach through which conditioned air escapes. Surprisingly, these gaps are virtually never sealed during the new home construction process. In fact, when typical new homes are tested with a Blower Door for air leakage, the volume of air lost through these spaces into the attic can be as much as 2 to 3 total air changes per day, or roughly equivalent to leaving a double hung window open 4 to 5 inches or more on a cold winter day. The attic insulation above these gaps provides no defense. In spite of the high “R-value” of fiberglass, it does not stop air movement through it. Therefore, virtually every house in the U.S. was (and still is) built with pathways for continuous loss of air into the attic and covered with insulation that is ineffective in stopping the air movement.
Conventional methods employed to reduce this energy loss include dispensing an unshaped bead of caulk and allowing it to cure before the drywall is installed. This bead is highly ineffective since it becomes very rigid and creates wider voids than a wall without the bead. The bead is also objectionable to builders and drywall installers since it may not enable the desirable close fit of wallboards.
Another approach to seal gaps from the home into the attic is to apply a bead of mastic or standard caulking and to install the drywall before the bead hardens. However, this bead is often non-existent after the drywall is installed. When the drywall is slid up the wall and into position during installation, the leading edge of the drywall wipes away most of the sealant bead and it remains on the edge of the drywall (in a totally ineffective location) rather than behind the drywall where it needs to be. Attempts to change the installation habits of drywall hangers to preserve the bead have been unsuccessful. The installers claim that the drywall sheets are too heavy and awkward to gently place them against the wall, and then hold them steady long enough to nail them into position without disrupting an uncured bead of caulk.
Still another sealing method to seal gaps from the home into the attic is to use a commercially available foam tape or weather strip instead of the bead of caulk. However, this method is ineffective since the drywall doesn't slide over the blunt edge of the weatherstrip tape. Instead the tape is sheared loose from the top plate by the drywall being slid into place and is never replaced. It is unreasonable to expect that a drywall Installer, being paid on a piece-work basis, would reattach every piece of weather strip that tears loose. In most cases, the tape simply “disappears” or remains on the leading edge of the drywall, and the homeowner is the loser, because the homeowner does not receive the energy saving device the owner thought he or she was buying.
Accordingly, there is a need to provide a method and structure to seal the air gaps in houses and commercial buildings to reduce the energy losses associated with air leaking through unsealed air gaps into the attic.